1. Field of the Invention
The invention relates to an image scanning apparatus, more particularly to an image scanning apparatus that utilizes a contact image sensor (CIS) module and that has a carrier.
2. Description of the Related Art
A contact image sensor (CIS) module is a high modular optical sensor module, which includes an optical lens, a sensing component and a photoelectric conversion circuit. Since the CIS module is small, it is widely used in flatbed image scanners so as to reduce an overall volume or size of the machine.
However, because the depth of field (DOE) of the CIS module is only plus or minus 0.3 mm, how to make the CIS module in steady contact with a transparent glass plate during a scanning process of a flatbed image scanner becomes a primary key in obtaining high quality scanned images. As such, many different inventions and designs have been disclosed, such as Taiwanese Patent Numbers TW364709, TW381801, and TW420335. Each of these patents mainly uses a carrier box to accommodate the CIS module, and then through an elastic structure that is disposed between the carriage box and a transmission device which guides movement of the carrier box or that is disposed between the carriage box and the CIS module to provide an upward supporting force, the CIS module can be kept in contact with the transparent glass plate during scanning. However, because the carrier box not only occupies a substantial space of an inner portion of the flatbed image scanner so that the overall volume or size of the machine cannot be effectively reduced, the number of the assembly process and the assembly component thereof are also increased. The purpose of lowering the costs and having a small, light and thin size cannot thus be easily achieved.